The present invention relates generally to a projection screen apparatus, and more particularly, to a motordriven projection screen apparatus.
While the size of the projection screen is not of the essence, these screens which are intended for use with the present invention are generally quite large, ranging in width from 5 to 14 feet, or more. They are the type of screens which are frequently found in auditoriums, in school rooms or in conference rooms. They are remotely controlled electrically by a small electric motor having a rotatable shaft which is operatively coupled to a large roller. The roller is generally journaled in a casing and the casing houses both the roller and the electric motor. The screen is, of course, rolled upon the roller when the screen is moved to a closed position and unrolled from the roller when it is moved to an exposed viewing position.
The apparatus is generally quite large and heavy and since it is also quite long, it is extremely cumbersome and, therefore, difficult to handle. The casings of such apparatus are frequently mounted in a recess in the ceiling by supporting brackets. Sometimes they are mounted high on a wall or behind a valance depending from the ceiling. In any event, the screens are frequently mounted in close quarters in fairly inaccessible positions.
The electrical motors employed to drive these screens are generally quite small relative to the loads under which they are expected to operate. Hence, they are susceptible to a failure more frequently than the screen, the roller or the other mechanical parts. Heretofore, these motors have been built-in as a part of the casing itself thereby permanently coupling the motor to a journal of the roller. Thus, when the mechanism failed to operate or required minor adjustment, it was necessary to remove the entire casing including the motor and the roller even though the majority of problems involved the electric motor. Removal of the apparatus often takes two or more men because the long device is heavy and awkward. In addition, the entire unit has to be shipped back to the factory so that the mechanical or electrical deficiency can be rectified. In shipping the entire unit, the delicate parts of the projection screen have to be shipped with the rugged parts of the screen, which, in light of the hazards of shipment, generally causes further mechanical or electrical problems.
Because of the lack of easy accessibility to the motor and the need for removal of the entire apparatus, undue expense needlessly accrued for repair or adjustment of motor-driven projection screens.